Magnetic position sensors are devices that generate a change in electronic signal output that is indicative of the relative movement of a mechanical component, such as, for example, a control shaft or rotor plate in the case of rotational position sensors or a carrier mechanism or linkage in the case of linear position sensors. In some instances, the change in electronic signal output is achieved without physical contact between the magnetic sensor circuit and the magnetic sensing element. These types of sensors are typically referred to in the industry as non-contacting magnetic position sensors.
With regard to non-contacting magnetic position sensors, one or more magnets may be used to generate a magnetic field having a magnetic field strength or flux density that varies as a function of the linear or rotational position of the mechanical component being monitored. The magnitude of the magnetic field strength is measured by an appropriate measuring device or detector, such as, for example, a Hall-effect element or magneto-resistive element. The value of the measured field intensity is translated through the measuring device to a voltage or current value that is uniquely representative of the relative rotational or linear position of the mechanical component being monitored. The electronic signal output provided by the magnetic position sensor is preferably a substantially linear representation of the relative rotational or linear position of the mechanical component being monitored. In addition to providing a substantially linear electronic signal output, minimizing hysteresis is also a desirable feature in most magnetic sensor applications.
In certain applications of magnetic position sensors, it is desirable to provide two redundant electronic output signals that are representative of the relative rotational or linear position of the mechanical component being monitored. For example, redundant electronic output signals are sometimes used in the automotive and transportation industries to monitor the status and position of critical systems or components. The redundant electronic signal outputs may be used to provide a back-up in the event that one of the signal outputs fails or becomes unreliable and/or may be used to provide verification or confirmation as to the accuracy and precision of the signal outputs.
In the past, attempts have been made to co-locate two measuring devices or detectors at the same position within a single magnetic field in an attempt to obtain identical electronic signal outputs. However, as should be appreciated, positioning of the measuring devices at precisely the same physical location is impossible. As a result, some differential is inherently present in the electronic signal outputs generated by the measuring devices.
Size and cost are usually a priority in magnetic position sensor designs, particularly in applications involving the automotive and transportation industries. For these applications, a compact magnetic circuit design that can be applied to a wide variety of applications and physical configurations, as well as maintaining a degree of simplicity that will be reflected in a reduced sensor cost, is desirable. Additionally, performance can not be compromised, and the ability to provide a relatively compact and inexpensive magnetic position sensor with good linearity and hysteresis characteristics is desirable.
Thus, there is a general need in the industry to provide an improved magnetic position sensor having dual electronic outputs. The present invention meets this need and provides other benefits and advantages in a novel and unobvious manner.